feat(pkg-config): allow reading PKG_CONFIG_ARGN

Signed-off-by: Antonio Nuno Monteiro <[email protected]>

CHANGES.md

@@ -1,6 +1,9 @@
 Unreleased
 ----------
 
+- Read `pkg-config` arguments from the `PKG_CONFIG_ARGN` environment variable
+  (#1492, #7734, @anmonteiro)
+
 - Correctly set `MANPATH` in `dune exec`. Previously, we would use the `bin/`
   directory of the context. (#7655, @rgrinberg)
 

otherlibs/configurator/src/v1.ml

@@ -616,6 +616,7 @@ let which t prog =
 module Pkg_config = struct
   type nonrec t =
     { pkg_config : string
+    ; pkg_config_args : string list
     ; configurator : t
     }
 
@@ -625,8 +626,13 @@ module Pkg_config = struct
       | s -> s
       | exception Not_found -> "pkg-config"
     in
+    let pkg_config_args =
+      match Sys.getenv "PKG_CONFIG_ARGN" with
+      | s -> String.split ~on:' ' s
+      | exception Not_found -> []
+    in
     Option.map (which c pkg_config_exe_name) ~f:(fun pkg_config ->
-        { pkg_config; configurator = c })
+        { pkg_config; pkg_config_args; configurator = c })
 
   type package_conf =
     { libs : string list
@@ -688,7 +694,8 @@ module Pkg_config = struct
       let run what =
         match
           String.trim
-            (Process.run_capture_exn c ~dir ?env t.pkg_config [ what; package ])
+            (Process.run_capture_exn c ~dir ?env t.pkg_config
+               (t.pkg_config_args @ [ what; package ]))
         with
         | "" -> []
         | s -> String.extract_blank_separated_words s

otherlibs/configurator/test/blackbox-tests/pkg-config-args.t/run.t

@@ -22,13 +22,13 @@ These tests show that setting `PKG_CONFIG_ARGN` passes extra args to `pkg-config
   -> process exited with code 0
   -> stdout:
    | gtk+-quartz-3.0
-  run: $TESTCASE_ROOT/_build/install/default/bin/pkg-config --cflags gtk+-quartz-3.0
+  run: $TESTCASE_ROOT/_build/install/default/bin/pkg-config --static --cflags gtk+-quartz-3.0
   -> process exited with code 0
   -> stdout:
-   | --cflags
+   | --static--cflags
    | gtk+-quartz-3.0
-  run: $TESTCASE_ROOT/_build/install/default/bin/pkg-config --libs gtk+-quartz-3.0
+  run: $TESTCASE_ROOT/_build/install/default/bin/pkg-config --static --libs gtk+-quartz-3.0
   -> process exited with code 0
   -> stdout:
-   | --libs
+   | --static--libs
    | gtk+-quartz-3.0

src/dune_rules/pkg_config.ml

@@ -20,8 +20,14 @@ module Query = struct
     | Libs s -> sprintf "%s.libs" s
     | Cflags s -> sprintf "%s.cflags" s
 
-  let to_args t : _ Command.Args.t list =
+  let to_args t ~env : _ Command.Args.t list =
+    let env_args : _ Command.Args.t =
+      match Env.get env "PKG_CONFIG_ARGN" with
+      | Some s -> As (String.split_on_char ~sep:' ' s)
+      | None -> Command.Args.empty
+    in
     Hidden_deps Dep.(Set.singleton universe)
+    :: env_args
     ::
     (match t with
     | Libs lib -> [ A "--libs"; A lib ]
@@ -59,9 +65,19 @@ let gen_rule sctx ~loc ~dir query =
   match bin with
   | Error _ -> Memo.return @@ Error `Not_found
   | Ok _ as bin ->
-    let command =
+    let* command =
+      let+ env =
+        let* dune_version =
+          let+ expander = Super_context.expander sctx ~dir in
+          expander |> Expander.scope |> Scope.project
+          |> Dune_project.dune_version
+        in
+        let* env_node = Super_context.env_node sctx ~dir in
+        if dune_version >= (3, 8) then Env_node.external_env env_node
+        else Memo.return Env.empty
+      in
       Command.run ~dir:(Path.build dir) ~stdout_to:(Query.file ~dir query) bin
-        (Query.to_args query)
+        (Query.to_args ~env query)
     in
     let+ () = Super_context.add_rule sctx ~loc ~dir command in
     Ok ()